The present invention relates generally to lasers, and more particularly, to a single focus backward Raman laser.
The present design for eyesafe Raman lasers incorporates a Raman half-resonator. This design is very sensitive to pump laser resonator mirror misalignment. In addition, the Raman beam divergence is much worse than that of the pump (typically two times worse). Backward Raman lasers on the other hand, have much better Raman beam divergence (typically no worse than 20 to 30% greater than the pump). They are also less sensitive to optics misalignment. A multiple focus backward Raman laser, which was a previous backward laser design of the assignee of the present invention, is relatively large and has more parts than the conventional half-resonator design. Also, the gas at each focus must be circulated for pulse repetition frequencies of greater than about 10 Hz. This last fact greatly increases the complexity and cost of the multiple focus backward Raman laser for laser systems with pulse repetition frequency requirements of greater than 10 Hz.
Therefore, it would be an advantage to have an efficient backward Raman laser that is less complex and more compact than a multiple focus backward Raman laser, and which provides substantially identical Raman conversion efficiency and beam divergence.